I recently found these on Amazon for $15.90 / pair including shipping and took a chance on them. (I think they are also available direct from Strike Industries). They also offer thin grips and other textures, though the price goes up for them.

These are a molded synthetic in a golf-ball design, but much less aggressive than most. Still, they provide me with plenty of traction. They are square-bottomed, pin-covered, and cut for an ambi safety.